Early childhood caries is a serious pediatric health problem that disproportionately impacts children of lower socioeconomic status. In the U.S., early childhood caries affects 2 to 20% of pre-school children. Despite the general appreciation for the magnitude of childhood dental problems and the role of dietary sugars in the development of caries, there are critical gaps in our knowledge regarding how best to characterize the cariogenicity of child diet, what aspects of child diet are most important in the development of caries, and how dental treatment influences subsequent dietary patterns. The proposed exploratory/developmental research makes use of a rich complement of dental and dietary data being collected prospectively on 900 children as part of project within the Northeast Center for Research to Evaluate and Eliminate Dental Disparities. Low-income predominantly non-white children ages 2 to 6 years are being studied at three time points over a 12-month period. Equal numbers of children with severe early childhood caries and caries-free control children have been enrolled. A cariogenicity classification system will be developed based on foods identified by 24-hour diet recall interview and food frequency questionnaire, and used to systematically develop and test a pediatric "dietary cariogenicity index" to represent total dietary cariogenicity based on both the physical form and timing of food consumed. Secondarily, we will explore comprehensively the impact of S-ECC on dietary patterns, and evaluate changes in dietary patterns and dietary cariogenicity following comprehensive dental treatment. Collectively, these activities will improve our ability to characterize child diets with methodology relevant for oral health, and to inform prevention efforts and our ability to intervene in children with early childhood caries. Project Narrative: Improved methodology for the study of oral health/nutrition linkages as well as better understanding of the associations between eating patterns and early childhood caries are urgently needed. Together these advances will support increasingly focused clinical research in prevention and treatment efforts aimed at early childhood caries, a condition which disproportionately impacts children of racial/ethnic minorities as well as those of lower socioeconomic status.